The present invention relates to a device in powdered inhalators intended to be used for local administration of drugs to the respiratory tract and lungs of a patient.
There are different types of powder inhalators, for example those which operate with hard gelatin capsules from which the pharmacologically active compound is released during inhalation through the inhalator, and those which dose the pharmacologically active compound directly into the air conduit by means of a special dosing unit, said compound being administered to patients during inhalation through the inhalator. All substances which are used in such inhalators are atomized or micronized so that the main fraction of the substance is within the particle size range which is termed the respirable range, that is, particles smaller than 5 .mu.m. This applies both to inhalators operating with pure active compound and to those where the active compound is mixed with suitable diluting agents such as lactose, sucrose etc. The active compound is enclosed, without carrier substance or when appropriate together with carrier substance, in hard gelatine capsules or directly in a storage unit in the inhalator, which storage unit is connected to a suitable dosing unit incorporated in the powder inhalator. When the substance is to be released from the hard gelatine capsule or from the dosing unit into the air conduit of the powder inhalator, it is essential that the largest possible quantity of primary particles is obtained in the respirable range, that is, smaller than 5 .mu.m, at flows which can be generated by a patient suffering from disease of the respiratory tract. A sufficient quantity of particles smaller than 5 .mu.m can be obtained to achieve a therapeutic effect by means of a particle disintegrating construction according to US-A-4 524 769, in which a constriction in the nozzle unit increases the flow velocity of the inhalation air and a propeller contributes to an increase in the quantity of particles in the respirable range. This construction implies, however, that movable parts are used in the nozzle unit.